Occupational Medicine Advance Access originally published online on February 22, 2007
Occupational Medicine 2007 57(4):290-293; doi:10.1093/occmed/kqm004
© The Author 2007. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
Acute respiratory symptoms among sisal workers in Tanzania
Akwilina V. Kayumba1,2,3,
Magne Bråtveit2,
Yohana Mashalla4 and
Bente E. Moen2
1 Centre for International Health, University of Bergen, Bergen, Norway
2 Department for Public Health and Primary Health Care, Section for Occupational Medicine, University of Bergen, Bergen, Norway
3 Directorate of Occupational Health Services, Tanzania Occupational Health Services, PO Box 3520, Dar Es Salaam, Tanzania
4 Department of Physiology, Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania
Correspondence to: Akwilina V. Kayumba, Department for Public Health and Primary Health Care, Section for Occupational Medicine, University of Bergen, Kalfarveien 31, N-5018 Bergen, Norway. Tel: +47 55 58 61 00; fax: +47 55 58 61 05; e-mail: akwilina.kayumba{at}gmail.com
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Abstract
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Background Few studies have focused on respiratory health effects
among sisal workers.
Aim To report on the prevalence of acute respiratory symptoms among sisal processors.
Methods We interviewed 163 dust-exposed brushing and decortication workers and 31 low-exposed security workers from six sisal estates in Tanzania using a modified symptom score questionnaire to determine the prevalence of acute respiratory symptoms during work. Groups were compared using chi-square tests, Fisher's exact tests, t-tests and logistic regression, adjusting for confounding factors.
Results After the first working day of the week, 73% of the brushing workers reported dry cough, 66% sneezing, 65% productive cough, 63% running nose and 34% stuffy nose. Brushing workers had a significantly higher prevalence of these symptoms than decortication workers. Brushing and decortication workers had significantly more dry cough and sneezing than the control group of security workers, when adjusting for age, smoking, past respiratory diseases and residence.
Conclusion Processors of sisal fibre have a high prevalence of acute respiratory symptoms. More detailed studies on work and health in sisal estates are needed, including exposure studies.
Keywords Agricultural workers; respiratory symptoms; sisal
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Introduction
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Agriculture is the backbone of the economy of Tanzania, constituting
>50% of the gross domestic product [
1]. Sisal is an important
agricultural export product ranking Tanzania third in the sisal
export global market [
2]. The demand for sisal is increasing
due to increased awareness of the benefits of natural fibres,
development of new sisal products and power generation [
3,
4].
Little is known on respiratory effects among sisal workers,
but a few studies have shown higher prevalence of respiratory
symptoms among these workers [
5–
7]. No recent studies
have been performed among sisal workers in Tanzania. The aim
of this study was to determine the prevalence of acute respiratory
symptoms among sisal fibre processing workers.
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Methods
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A cross-sectional study was done between June and September
2005 among six of 28 actively producing sisal estates. These
six estates employed
1700 workers in December 2004. Each estate
had a processing factory comprising an outdoor decortication
plant for fibre extraction and a brushing hall (
Figure 1) for
scraping and brushing of dried sisal fibres.
All workers in the brushing and decortication departments were
invited to take part as a dust-exposed group. Security workers
presumed to have low exposure to sisal dust were randomly selected
as controls from a list of such workers. A modified optimal
symptom score questionnaire on respiratory symptoms [
8] and
parts of a modified British Medical Research Council questionnaire
[
9] were used for interviewing all consenting workers immediately
after the work shift on their first day of the week (Monday).
Questions were asked about acute respiratory symptoms occurring
since work started on this particular Monday. The symptoms were
dry cough, productive cough, shortness of breath, wheezing,
stuffy nose, running nose and sneezing. Workers were requested
to rate the symptoms according to severity on a five-point scale:
none at all, mild, moderate, severe and very severe. Before
data analysis, the rated symptoms were dichotomized into yes
(mild, moderate, severe or very severe) or no (never). The workers
were asked if they used any dust masks during work. Information
on past respiratory health problems (bronchitis, asthma, tuberculosis
and atopy) was obtained as ‘yes’ or ‘no’.
In addition, the following sociodemographic information was
collected: age (years), residence (in estate camp or outside),
smoking habits (current smokers) and any history of past employment
in dusty industry. The survey obtained ethical clearance from
both Norwegian and Tanzanian medical ethics authorities, and
the interviewed workers signed an informed consent. The first
author administered all interviews.
SPSS version 13 for Windows was used for statistical analysis. t-test was used for comparing age. Chi-square tests and Fisher's exact tests (for values <5) were used for analysing differences in categorical variables. Logistic regression was performed for acute respiratory symptoms adjusting for age, current smoking, area of residence (in the camp or outside the camp) and past respiratory illnesses (pneumonia, bronchitis, asthma or tuberculosis). Statistical significance was set at 5%.
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Results
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In all, 165 dust-exposed workers and 32 controls participated.
Except for one security worker, all invited workers responded.
One hearing-impaired decortication worker and one brushing worker
suffering from malaria at the time of the study could not complete
interviews and hence were excluded from the analysis. Brushing
workers and decortication workers differed significantly in
both mean age and mean duration of employment in the current
job (
Table 1). The prevalence of current smoking was significantly
higher among the exposed groups (brushing and decortication)
than among the security workers (
Table 1). The prevalence of
past respiratory diseases was higher (
P < 0.05) among the
exposed group than among the security workers (
Table 1). Except
for one worker who used his simple personal dust mask, no other
workers reported using respiratory protection equipment.
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Table 1. Demographic characteristics, past respiratory illnesses and the prevalence of acute respiratory symptoms among 194 workers in six sisal estates
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Workers in the brushing department had a significantly higher
prevalence of dry cough, productive cough, stuffy nose, running
nose and sneezing than decortication workers (
Table 1). The
combined exposed group of brushing and decortication had a significantly
higher prevalence of dry cough, sneezing, wheezing and shortness
of breath than the control security workers (
Table 1). After
adjusting for the effects of age, current smoking, past respiratory
illnesses and area of residence, the exposed group (brushing
and decortication) still had significantly higher odds ratio
for sneezing and dry cough compared to security workers (
Table 2).
Age and years at current job were strongly correlated (
P <
0.01), hence of these parameters only age was included in this
analysis. Also with the same adjustments, workers in the brushing
department had significantly higher prevalence of sneezing,
stuffy nose, dry cough, running nose and productive cough compared
to decortication workers (
Table 2).
View this table:
[in this window]
[in a new window]
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Table 2. Acute respiratory symptoms among sisal processing workers compared to security workers and among two groups of sisal processing workers (decortication workers and workers in brushing) by use of logistic regression, adjusting for current smoking, age, past respiratory illnesses and residence
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Discussion
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Our study found a high prevalence of acute respiratory symptoms
in dust-exposed sisal workers. This is in agreement with a study
in Croatia [
10]. In our study, workers in the brushing departments
had the highest prevalence of acute symptoms which is in agreement
with the findings of Mustafa
et al. [
7]. Low prevalence of byssinosis
which is considered to be among chronic obstructive respiratory
diseases was found in two other studies among sisal workers,
but these also reported low dust levels [
5,
6]. Our study focused
on acute symptoms. Lack of exposure measurements and information
on chronic respiratory symptoms including chest tightness in
our study does not allow for further comparison with these studies.
In our study, the workers in the brushing department had more nasal symptoms when compared to workers in decortication. This could be due to differences between the departments in both the level and type of airborne exposure.
The high prevalence of acute respiratory symptoms among the sisal production workers might also be associated with exposure to the aerosol and sisal fibre dust in the sisal processing areas. Exposure studies as well as improvements of the work environment ought to be performed.
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Conflicts of interest
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None declared.
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Acknowledgements
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We are grateful to the owners of the sisal estates, the workers
who voluntarily participated in the study and to Martin Nampesha
from the Tanga regional factory inspectorate office for introducing
us to the factories in the estates. This study was largely financed
by the Norwegian Council of University Committee for Development
Research and Education and partly by the Norwegian State Education
Loan Fund (Lånekassen).
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References
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Abstract
Introduction